This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. Primary support for the subproject and the subproject's principal investigator may have been provided by other sources, including other NIH sources. The Total Cost listed for the subproject likely represents the estimated amount of Center infrastructure utilized by the subproject, not direct funding provided by the NCRR grant to the subproject or subproject staff. INTRODUCTION: Concerns regarding alopecia in nonhuman primates are justified given that hair performs many essential functions. METHODS: The occurrence of alopecia is often attributed to the level of psychological wellbeing, and behavioral causes have become a routine, unconfirmed default diagnosis for alopecia in captive nonhuman primates. However, before attributing alopecia to abnormal behavior, it is necessary to rule out medical causes of alopecia. In this study, a medical and behavioral assessment of animals with and without alopecia was performed with the aim of designing a guide to approaching cases of nonhuman primate alopecia. The well-established algorithm for evaluation of alopecia in companion animal species was used as the basis for the medical evaluation. In addition, a behavioral evaluation was used to assess animals for the presence or absence of hair plucking. The hypothesis tested was that the commonly used diagnostic evaluation for alopecia in companion animal species is not applicable to nonhuman primates. RESULTS/DISCUSSION: Aside from the histopathology and behavioral assessment differences, few clinically relevant significant differences were found between animals with alopecia and control animals. As a result, the hypothesis was confirmed and we determined that application of the diagnostic plan for alopecia that is used in companion animal species to nonhuman primates is a practice that needs to be reexamined.